Primitive and incomplete support for parsing scalar as null, boolean, number and date
Merge https://github.com/collections/YAML.framework

Conflicts:
	YAMLSerialization.m
Indentation and other whitespace fixes after merge
Made unit tests execute well in Xcode 5
Added podspec
Fixed memory corruption problem
remove unnecessary semi-colons (keep compiler warnings quiet).
Cast to NSMutableArray to avoid a compiler warning about ambiguous -addObject:. This is not likely to be something normally encountered, as the other -addObject: is coming out of the Nimbus 3rd party library.
add autorelease to avoid possible memory leak.

The various "parse xxx" methods do return auto-released objects, and so the string object ought to do the same.
So I was wrong. Do NOT autorelease the string -- it gets explicitly released later on. Instead, just use some preprocessor directives to suppress the static analyzer.
Do not consider an empty string to be NSNull; consider it an empty string. And if somehow we do get a nil string, do consider that an NSNull.

See: http://yaml.org/type/null.html

"A null value is used to indicate the lack of a value. This is typically converted into any native null-like value (e.g., undef in Perl, None in Python). Note that a null is different from an empty string and that a mapping entry with some key and a null value is valid and different from not having that key in the mapping."

I'd have to look into my case further (it was a mapping entry with some key and "" for the value, so truly an empty string, not a NULL). For now, this is easiest for me to handle. But it should be revisited for a cleaner solution.
Merge pull request #2 from barz/barz-master

merging prior changes.